This invention relates generally to frequency measuring apparatus and more particularly to instantaneous frequency measurement (IFM) apparatus adapted for use in determining the frequency of radio frequency signals.
As is known in the art, instantaneous frequency measurement apparatus generally include analog components, such as delay lines and frequency discriminator circuits, to determine the frequency of radio frequency signals. While such apparatus may be adequate in many applications they are generally large in size and relatively expensive. The use of digital components as digital counters in the GHz frequency range has heretofore generally not been successful because such counters cannot accurately respond to signals having frequencies in the GHz frequency range.